1. Technical Field
This invention relates generally to sleeves for protecting elongate members, and more particularly to wrappable sleeves that provide protection to elongate members contained within the sleeves against at least one of electromagnetic interference, radio frequency interference, and electrostatic discharge.
2. Related Art
It is known that electromagnetic interference (EMI), radio frequency interference (RFI), and electrostatic discharge (ESD) pose a potential problem to the proper functioning of electronic components caused by interference due to inductive coupling between nearby electrical conductors and propagating electromagnetic waves. For example, electrical currents in conductors associated with an electrical power system in an automobile may induce spurious signals in various electronic components, such as an electronic module which controls the functioning of the engine. Such interference could downgrade the performance of control modules or other components in the vehicle, thereby causing the vehicle to act other than as desired.
Similarly, inductive coupling between electrical wiring and the lines carrying data in a computer network or other communication system may have a corrupting effect on the data being transmitted over the network.
The adverse effects of EMI, RFI and ESD can be effectively eliminated by proper shielding and grounding of EMI, RFI and ESD sensitive components. For example, wires carrying control signals which may be subjected to unwanted interference may be shielded by using a protective sleeve. The sleeves are formed at least in part from standard round (as viewed in lateral cross-section) electrically conductive members, with the conductive members typically being grounded via a drain wire interlaced with the sleeve during manufacture of the sleeve. Typically, the conductive members take the form of round polymeric filaments, such as nylon, coated with a conductive metal, such as silver. The ground members are known to be intertwined along the length of the sleeve, and subsequently pulled away from the wall of the sleeve for attachment to a source of ground; however, upon pulling the ground members outwardly from the sleeve, a potential problem arises from the creation of an opening in the wall of the sleeve, through which EMI, RFI and/or ESD can pass.
While such RFI, EMI, and ESD sleeving can be generally effective at eliminating electrical interference, the sleeving can be relatively expensive in manufacture, particularly when expensive coatings, such as silver, are used, and can exhibit some inefficiency in conductive connections between the round conductive fiber constituents. In addition, if coated members are used, the conductive coating can be worn off, thereby impacting the ability of the sleeving to provide RFI, EMI, and/or ESD protection. Further yet, when round wire or round conductors are used to construct the entirety of protective barrier against RFI, EMI and ESD of the sleeve, the round conductive members are is typically provided as a fine wire, thereby having low tensile strength, and thus, tending to being damaged and broken in use, thereby reducing the shielding effectiveness of the sleeve and possibly causing wear against the protected wires within the sleeve and resulting in a potential source of arcing. In addition, with the wires being round, and further having a relatively small diameter, a large number of wires and/or turns/passes of the wire are needed to create an effective barrier to RFI, EMI, ESC, and thus, the mass and thickness of the sleeve wall is generally increased significantly, and further, the flexibility of the sleeve is generally significant reduced. Accordingly, a need for RFI, EMI, ESD shielding which is more economical in manufacture, flexible, light weight, reduced in size, efficient in use, and more reliable against wear and having an increased useful life, is needed.
A sleeve manufactured in accordance with the present invention overcomes or greatly minimizes at least those limitations of the sleeves described above and achieves desired goals mentioned above, among others as will be readily recognized by one skilled in the art upon viewing the disclosure herein.